The present invention relates to a porous polymeric matrix containing at least one natural polymer and at least one synthetic polymer and optionally at least one cation. Furthermore, the present invention relates to a method of making a porous polymeric matrix involving mixing at least one natural polymer and inorganic salts with a solution containing at least one solvent and at least one synthetic polymer to form a slurry, casting the slurry in a mold and removing the solvent to form solid matrices, immersing the solid matrices in deionized water to allow natural polymer cross-linking and pore creation to occur simultaneously, and drying the matrices to create a porous polymeric matrix; wherein the matrix contains a cation. Also, a method of making a porous polymeric matrix, involving mixing at least one natural polymer in an aqueous solvent and mixing at least one synthetic polymer in an organic solvent, combining the mixtures and casting in a mold, and separately removing said aqueous solvent and said organic solvent to form a porous polymeric matrix; wherein the porous polymeric matrix does not contain a cation.
Polymers such as poly(lactide-co-glycolide)(p(LGA)) has been used clinically for tissue repair and organ regeneration for decades. Poly(lactide-co-glycolide), a hydrophobic polymer, is biocompatible, biodegradable, and easily processed into a variety of sizes and shapes which have good mechanical properties (Ma, P. X., and R. Langer, Fabrication of biodegradable polymer foams for cell transplantation and tissue engineering, In: Tissue engineering methods and protocols, J. Morgan and M. Yarmush, editors, Humana Press Inc., Totowa, N.J., 1999, p. 47-56; Lanza, R. P., et al., Principles of tissue engineering, Academic Press, San Diego, Calif., 1997; Patrick, C. W., et al., editors, Frontiers in tissue engineering, Pergamon, New York, 1998; Ma, P. X., et al., J. Biomed. Mater. Res., 54(2): 284-93 (2001)). Although p(LGA) will support cell attachment and cell growth, it does not impart signals to the cells (Langer, R., J. P. Vacanti, Science, 260: 920-6 (1993)). The inability to carry signal molecules limits the application of polymers such as p(LGA). This deficiency is currently overcome by synthesizing block or graft copolymers of lactic acid and lysine or other segments carrying side chain functional groups (Langer, R., J. P. Vacanti, Science, 260: 920-6 (1993); Ouchi, T. et al, Macromolecules, 3(5):885-8 (2002)). Through the functional groups, specific amino acid sequences can be attached. By this strategy, a number of new chemical entities have been provided. However, the preparation of such copolymers involves a series of cumbersome isolation, purification and identification procedures.
The present invention provides matrices, made of natural polymers (e.g., pectins) and synthetic polymers such as p(LGA) and optionally at least one cation, that retain the biomechanical strength of polymers such as p(LGA) yet also provide access for hydrophilic, bioactive substances.